Bismuth-Corlette Modified Bismuth-Corlette classification of perihilar cholangiocarcinoma

{
  "categories": [
    {
      "outcome_code": "I",
      "longitudinal_extent": "common_hepatic_duct_below_primary_right_left_confluence",
      "primary_confluence": "spared",
      "right_secondary_confluence": "spared",
      "left_secondary_confluence": "spared"
    },
    {
      "outcome_code": "II",
      "longitudinal_extent": "primary_right_left_hepatic_duct_confluence",
      "primary_confluence": "involved",
      "right_secondary_confluence": "spared",
      "left_secondary_confluence": "spared"
    },
    {
      "outcome_code": "IIIa",
      "longitudinal_extent": "primary_confluence_and_right_secondary_ductal_confluence",
      "primary_confluence": "involved",
      "right_secondary_confluence": "involved",
      "left_secondary_confluence": "spared"
    },
    {
      "outcome_code": "IIIb",
      "longitudinal_extent": "primary_confluence_and_left_secondary_ductal_confluence",
      "primary_confluence": "involved",
      "right_secondary_confluence": "spared",
      "left_secondary_confluence": "involved"
    },
    {
      "outcome_code": "IV",
      "longitudinal_extent": "both_right_and_left_secondary_ductal_confluences_or_multifocal_discontinuous_bilateral_disease",
      "primary_confluence": "usually_involved",
      "right_secondary_confluence": "involved",
      "left_secondary_confluence": "involved"
    }
  ],
  "identity_and_scope": {
    "intended_use": "Describe longitudinal ductal extension of a suspected or confirmed perihilar cholangiocarcinoma before intervention.",
    "classification_unit": "one_perihilar_tumor_at_one_preintervention_staging_timepoint",
    "lineage": "The framework was introduced by Bismuth and Corlette in 1975 and modified in the 1992 surgical strategy publication; identify the current five-type form as modified Bismuth-Corlette.",
    "nomenclature": "Use perihilar cholangiocarcinoma for tumors arising at the hepatic hilum; retain hilar or Klatskin only as recognized synonyms when matching source records.",
    "outside_scope": [
      "vascular_invasion",
      "lobar_atrophy",
      "nodal_stage",
      "distant_metastases",
      "future_liver_remnant",
      "AJCC_stage",
      "Blumgart_stage",
      "resectability",
      "prognosis",
      "automatic_resection_or_drainage_route"
    ]
  },
  "anatomy_gate": {
    "primary_confluence": "Junction of the right and left hepatic ducts forming the common hepatic duct.",
    "secondary_confluences": "First major intrahepatic right and left sectoral duct junctions; right anterior/posterior and left sectoral anatomy or variants must be mapped explicitly.",
    "variant_rule": "Ductal variants can change the surgical meaning of a nominal side. Report the actual ducts involved and do not infer a type from right/left wording without a mapped biliary tree.",
    "longitudinal_only_rule": "Radial mass size or contact with vessels does not change the Bismuth code unless longitudinal ductal involvement crosses a defining confluence."
  },
  "classification_algorithm": [
    {
      "step": 1,
      "if": "both_right_and_left_secondary_confluences_involved_or_multifocal_discontinuous_bilateral_ductal_disease",
      "output_code": "IV"
    },
    {
      "step": 2,
      "if": "primary_confluence_and_right_secondary_confluence_involved_with_left_secondary_confluence_spared",
      "output_code": "IIIa"
    },
    {
      "step": 3,
      "if": "primary_confluence_and_left_secondary_confluence_involved_with_right_secondary_confluence_spared",
      "output_code": "IIIb"
    },
    {
      "step": 4,
      "if": "primary_confluence_involved_and_both_secondary_confluences_spared",
      "output_code": "II"
    },
    {
      "step": 5,
      "if": "tumor_below_primary_confluence_with_confluence_spared",
      "output_code": "I"
    },
    {
      "step": 6,
      "if": "one_or_more_confluences_cannot_be_assessed",
      "output": "indeterminate_or_adjacent_type_range_with_missing_anatomy"
    }
  ],
  "decisive_boundaries": {
    "I_II": "Any primary confluence involvement is at least type II; tumor ending below it is type I.",
    "II_III": "Type II spares both secondary confluences. Extension into the right or left secondary confluence creates IIIa or IIIb respectively.",
    "III_IV": "Unilateral secondary-confluence involvement is type III; bilateral secondary-confluence involvement is type IV.",
    "multifocal_rule": "Discontinuous bilateral ductal foci may be represented as type IV in modified formulations; state the multifocal pattern rather than hiding it behind the numeral.",
    "stent_boundary": "Assign the pretreatment duct map before biliary stenting whenever possible because decompression, inflammation and devices can obscure longitudinal tumor extent."
  },
  "imaging_and_structured_staging": {
    "CT": "Use multiphasic contrast-enhanced CT of chest, abdomen and pelvis to evaluate arterial and portal venous involvement, adjacent invasion, nodes and distant metastases.",
    "MRI_MRCP": "Use contrast-enhanced MRI with MRCP to map the primary and both secondary biliary confluences, longitudinal intraductal extent, satellites and ductal variants.",
    "mandatory_duct_map": [
      "inferior_tumor_margin",
      "primary_confluence",
      "right_secondary_confluence",
      "left_secondary_confluence",
      "right_anterior_and_posterior_sectoral_ducts",
      "left_sectoral_ducts",
      "ductal_variants",
      "multifocal_or_skip_disease"
    ],
    "mandatory_non_Bismuth_fields": [
      "hepatic_artery_contact_as_preserved_fat_plane_abutment_below_180_degrees_encasement_above_180_degrees_stenosis_or_occlusion",
      "portal_vein_contact_as_preserved_fat_plane_abutment_below_180_degrees_encasement_above_180_degrees_stenosis_or_occlusion",
      "lobar_or_segmental_atrophy",
      "adjacent_organ_or_parenchymal_invasion",
      "regional_and_distant_nodes",
      "distant_metastases",
      "future_liver_remnant_volume_quality_and_drainage"
    ],
    "completeness_rule": "A Bismuth code without separate vascular, atrophy, metastatic and future-liver-remnant fields is not a complete resectability assessment."
  },
  "modern_staging_boundary": {
    "AJCC": "Use the current AJCC system for formal anatomic stage rather than treating Bismuth as a cancer stage.",
    "Blumgart": "Blumgart or an equivalent multidisciplinary framework adds portal-vein involvement and lobar atrophy to biliary extent for resectability assessment.",
    "evidence_boundary": "Modern analyses cited by EASL found AJCC more informative for resectability and survival, and expert centers have resected selected tumors across all Bismuth types.",
    "type_IV_rule": "Type IV is not synonymous with unresectable. Determine technical and oncologic resectability from bilateral ductal extent together with vessels, atrophy, metastases, future liver remnant, reconstruction options and center expertise."
  },
  "current_management_context": {
    "multidisciplinary_review": "Every potentially localized perihilar cholangiocarcinoma requires specialist hepatobiliary multidisciplinary review using high-quality preintervention imaging.",
    "resection_goal": "For localized disease, complete R0 resection is the curative-intent surgical goal when anatomically and physiologically feasible.",
    "types_IIIa_IIIb": "IIIa often prompts consideration of a right-sided or extended resection and IIIb a left-sided approach, but the final side and extent depend on ductal variants, vascular involvement, lobar atrophy, future liver remnant and achievable margins.",
    "type_IV": "Selected type-IV tumors may undergo complex resection or a protocolized transplant pathway at expert centers; the Bismuth label alone cannot select either path.",
    "future_liver_remnant": "Planning commonly targets more than 25-30 percent future liver remnant in healthy liver and may require more than 40 percent in perihilar cholangiocarcinoma with prolonged obstruction; volume, function and drainage must be individualized.",
    "biliary_drainage": "Avoid routine preoperative drainage. Consider it for cholangitis, renal failure, intractable pruritus, marked hyperbilirubinemia, neoadjuvant therapy, extensive planned surgery or a long wait; drain the intended future liver remnant when drainage is required.",
    "route_guard": "Do not choose endoscopic versus percutaneous drainage from Bismuth type alone. Current EASL guidance finds insufficient evidence to recommend one route universally for resectable disease requiring drainage.",
    "safety_rule": "Never emit right hepatectomy, left hepatectomy, trisectionectomy, drainage, unresectability or transplant eligibility as an automatic consequence of type I-IV."
  },
  "risk_and_interpretation": {
    "no_per_type_calibration": "No current guideline provides an independent calibrated survival probability for each Bismuth type.",
    "complexity_direction": "Higher ductal extent generally increases reconstruction and margin complexity, but does not monotonically determine operative candidacy or survival.",
    "actual_prognostic_factors": [
      "R0_margin_feasibility",
      "nodal_status",
      "distant_metastases",
      "vascular_invasion",
      "lobar_atrophy",
      "future_liver_remnant",
      "tumor_biology",
      "patient_fitness"
    ],
    "communication_rule": "Describe the exact involved confluences beside the type so a numeral never replaces the surgical anatomy."
  },
  "missing_input_behavior": [
    "If the primary confluence cannot be evaluated, withhold type I versus II and identify the needed MRCP or cholangiographic anatomy.",
    "If a secondary confluence is obscured by a stent or inadequate imaging, return the defensible adjacent range rather than forcing II, III or IV.",
    "If vascular, atrophy, metastatic or future-liver-remnant data are absent, provide the ductal type but mark resectability indeterminate.",
    "If right or left ductal anatomy is variant, name the variant and the specific involved ducts before selecting IIIa or IIIb."
  ],
  "agent_output_contract": [
    "modified_Bismuth_Corlette_type_or_explicit_uncertainty",
    "plain_language_primary_and_secondary_confluence_map",
    "pre_or_post_stent_imaging_provenance",
    "MRI_MRCP_and_multiphasic_CT_adequacy",
    "arterial_portal_venous_atrophy_nodal_and_metastatic_fields_separately",
    "future_liver_remnant_volume_quality_and_drainage",
    "AJCC_or_other_formal_stage_separately_when_available",
    "multidisciplinary_resectability_state_without_type_only_inference",
    "management_context_without_automatic_resection_or_drainage_route"
  ],
  "supporting_sources": [
    {
      "role": "original_framework",
      "citation": "Bismuth and Corlette. Surg Gynecol Obstet. 1975;140:170-178",
      "pmid": "1079096"
    },
    {
      "role": "modified_surgical_framework",
      "citation": "Bismuth et al. Ann Surg. 1992;215:31-38",
      "doi": "10.1097/00000658-199201000-00005",
      "pmid": "1309988",
      "pmcid": "PMC1242367"
    },
    {
      "role": "current_European_staging_and_management_context",
      "citation": "EASL CPG. J Hepatol. 2025;83:211-238",
      "doi": "10.1016/j.jhep.2025.03.007",
      "pmid": "40348685"
    },
    {
      "role": "current_multidisciplinary_anatomic_context",
      "citation": "Dar et al. World J Gastroenterol. 2024;30:1018-1042",
      "doi": "10.3748/wjg.v30.i9.1018",
      "pmid": "38577184",
      "pmcid": "PMC10989497"
    }
  ],
  "source_locator": "Bismuth and Corlette 1975, PMID 1079096, and Bismuth, Nakache and Diamond 1992, DOI 10.1097/00000658-199201000-00005, for classification lineage. EASL extrahepatic cholangiocarcinoma CPG 2025, DOI 10.1016/j.jhep.2025.03.007, sections on diagnosis/staging, radiology, resectability, surgery and biliary drainage. Dar et al. 2024, PMC10989497, Bismuth-Corlette, preoperative imaging, surgical resection and drainage sections for the multidisciplinary anatomy boundary."
}